1. Field of the Invention
This invention relates to a printing apparatus for performing printing on a print medium supplied from a roll of the print medium.
2. Description of the Related Art
Examples of such apparatus as above conventionally include an inkjet printing apparatus. The inkjet apparatus includes an inkjet printing station, a paper feeder, and a take-up roller. The inkjet printing station performs printing on a print medium (e.g., a web paper). The paper feeder holds a roll of the print medium, unwinds the print medium from the roll of print medium, and supplies the print medium to the inkjet printing station. The take-up roller winds up the printed print medium into a roll form. The inkjet printing station includes an inkjet heads for discharging ink droplets to the print medium, and a mechanism for moving the inkjet heads and the print medium relatively to each other.
Moreover, Japanese Patent Publication No. S61-257854 discloses a paper passing device in a web supply apparatus. The paper passing device supplies a paper fed out from an upper web-supply roll (a roll of an upper print medium) and a lower web-supply roll alternately. The paper passing device includes guide rails. A roller chain (hereinafter, referred to as a “chain”) is inserted into a gap between the guide rails. When an electric motor having a chain pulley (sprocket) being fitted therewith rotates, the chain moves along the guide rails, whereby a web transport bar for passing paper is moved.
However, the conventional inkjet printing apparatus has the following drawbacks. That is, the print medium is transported within the inkjet printing apparatus when the print medium is replaced or firstly subject to setting (also referred to as “loading”). The print medium is transported by putting hands of an operator into the inkjet printing apparatus along a transportation path of the print medium. Accordingly, this operation needs an experiential technique, time, and the like. For instance, the print medium provided with perforations or the thin print medium may tear. Thus, this operation is not easy for the operator. Such a drawback may arise.
The inkjet printing apparatus enables to support changes in specification. Specifically, the inkjet printing station except for the paper feeder and the take-up roller is divided depending on functions, and thus is formed by two or more units. For instance, the inkjet printing station includes three units, i.e., a print unit, a unit disposed upstream of the print unit, and a unit disposed downstream of the print unit. Moreover, the print unit performs four-color printing of, for example, KCMY (black, cyanogen, magenta, and yellow). When the print unit performs four-color printing, for example, with high definition, the print unit is upsized. Accordingly, the print unit is divided into two print units each having inkjet heads placed therein. In this case, one original print unit is replaced with two print units. Moreover, six-color printing is occasionally needed by adding a print unit of two-color (orange, green) printing to the print unit of four color prints.
As noted above, specifications of the inkjet printing apparatus can be changed by combining a plurality of units optionally. However, where the paper passing mechanism for transporting the print medium is adopted in the inkjet printing apparatus, the mechanism should be changed in accordance with combination of a plurality of units. Therefore, it was difficult to achieve a balance between adoption of the mechanism for transporting the paper and optical combination of a plurality of units.